1. Field of the Invention
The invention relates generally to capacity planning and bandwidth provisioning for access networks, and specifically, capacity planning and bandwidth provisioning for video, voice over IP (VoIP) and Internet data traffic over cable or digital subscriber line (DSL) access networks using sampled traffic to create a provisioning model. The invention also relates to video bandwidth planning associated with conversion of analog cable TV channels into digital channels.
2. Description of the Prior Art
Internet service providers frequently include a quality-of-service (QoS) guarantee in their service level agreements. The QoS guaranteed may include network availability and reachability. ISPs may also include end-to-end delay benchmarks within their networks in service level agreements. Such benchmarks may allow ISPs to provide better services to existing applications, such as web browsing, as well as to new emerging services such as IP telephony (VoIP) and Internet video, by providing guarantees of achieving such benchmarks. In addition, QoS gives an Internet provider an edge in an increasingly competitive marketplace, in that customers are able to receive VoIP and video, both time-sensitive applications, in such a manner that coherent voice and video streams are communicated.
The ability to plan and provision the capacity of access networks in such a way that the priority of time-sensitive applications is preserved, yet effective data rates are achieved in Internet applications, is critical to the business model of any Internet Service Provider (ISP). Measurement tools may monitor the network for performance statistics, and identify where the network provider needs to allocate more network resources. However, performance statistics alone cannot provide the precise amount and timing of capacity additions needed, especially at points that currently are not bottlenecks. Performance statistics are also of limited value when rapid subscriber growth or system consolidation is expected. In such cases planning errors can cause customer dissatisfaction if QoS levels fall, or wastage of expensive resources when provisioning is ad hoc or needlessly liberal. For several years there has been widespread rapid growth in the numbers of subscribers to internet access services provided by cable and telephone company ISPs. Holding other factors constant, we have found that subscriber growth produces nonlinear changes in the amount of bandwidth required to provide a constant QoS level. Thus it is crucial for bandwidth projections to take explicit account of subscriber growth, and to take advantage of associated economies of scale. VoIP service quality deteriorates rapidly with increasing delay (latency); however VoIP may rely on a ‘best efforts’ protocol. As a result there must be appropriate bandwidth provisioning not only for VoIP service itself but for other services that share physical facilities for transmission.
Because of ongoing evolution of internet applications and usages, it is also important that bandwidth provisioning tools be easily upgraded and customized to the needs of ISPs. For example, some ISPs have implemented monthly limits on downloads while others have not. To reflect the possible impact on subscriber usage patterns, we have included in our tools a traffic model for each case, as well as tool functionality to build a traffic model from the tool user's custom traffic statistics or a file containing a full busy hour traffic trace.
Therefore there is a need for an accurate bandwidth provisioning tool for ISPs, for both VoIP and data traffic, which is able to predict the demand for the network resources based on the network traffic characteristics and the number of subscribers after taking into account subscriber growth and other relevant factors. Further, these tools should be as clear and easy to use as possible, providing contextual help where appropriate. This predictive tool will enable the ISP to allocate scarce resources to the most advantageous effect, and to do this planning on a ‘just in time’ basis to optimize the enormous capital investment costs.